Piriformospora indica stimulates root metabolism of Arabidopsis thaliana

Piriformospora indica is a root-colonizing fungus, which interacts with a variety of plants including Arabidopsis thaliana. This interaction has been considered as mutualistic, as it leads to an increased mycelia dry weight and increased shoot fresh weight, respectively. So far, only indolic glucosinolates and phytohormones have been identified as major key players. In a comprehensive non-targeted metabolite profiling study by means of UPLC/ESI-QTOFMS and GC/EI-QMS we analyzed Arabidopsis thaliana’s roots, root exudates, and leaves of inoculated and non-inoculated plants and identified further biomarkers. Among them, the concentration of nucleosides, dipeptides, oligolignols, and glucosinolate degradation products was affected in the exudates. In the root profiles, nearly all metabolite levels increased upon co-cultivation, namely those of carbohydrates, organic acids, amino acids, glucosinolates, oligolignols, and flavonoids. In the leaf profiles, we detected by far less significant changes. We only observed an increased concentration in organic acids, carbohydrates, ascorbate, glucosinolates and hydroxycinnamic acids, and a decreased concentration in nitrogen-rich amino acids in inoculated plants.